ui/views/layout/box_layout.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/views/layout/box_layout.h"
   6
   7 #include "ui/gfx/geometry/rect.h"
   8 #include "ui/views/view.h"
   9
  10 namespace views {
  11
  12 BoxLayout::BoxLayout(BoxLayout::Orientation orientation,
  13                      int inside_border_horizontal_spacing,
  14                      int inside_border_vertical_spacing,
  15                      int between_child_spacing)
  16     : orientation_(orientation),
  17       inside_border_insets_(inside_border_vertical_spacing,
  18                             inside_border_horizontal_spacing,
  19                             inside_border_vertical_spacing,
  20                             inside_border_horizontal_spacing),
  21       between_child_spacing_(between_child_spacing),
  22       main_axis_alignment_(MAIN_AXIS_ALIGNMENT_START),
  23       cross_axis_alignment_(CROSS_AXIS_ALIGNMENT_STRETCH),
  24       default_flex_(0),
  25       minimum_cross_axis_size_(0),
  26       host_(NULL) {
  27 }
  28
  29 BoxLayout::~BoxLayout() {
  30 }
  31
  32 void BoxLayout::SetFlexForView(const View* view, int flex_weight) {
  33   DCHECK(host_);
  34   DCHECK(view);
  35   DCHECK_EQ(host_, view->parent());
  36   DCHECK_GE(flex_weight, 0);
  37   flex_map_[view] = flex_weight;
  38 }
  39
  40 void BoxLayout::ClearFlexForView(const View* view) {
  41   DCHECK(view);
  42   flex_map_.erase(view);
  43 }
  44
  45 void BoxLayout::SetDefaultFlex(int default_flex) {
  46   DCHECK_GE(default_flex, 0);
  47   default_flex_ = default_flex;
  48 }
  49
  50 void BoxLayout::Layout(View* host) {
  51   DCHECK_EQ(host_, host);
  52   gfx::Rect child_area(host->GetLocalBounds());
  53   child_area.Inset(host->GetInsets());
  54   child_area.Inset(inside_border_insets_);
  55
  56   int total_main_axis_size = 0;
  57   int num_visible = 0;
  58   int flex_sum = 0;
  59   // Calculate the total size of children in the main axis.
  60   for (int i = 0; i < host->child_count(); ++i) {
  61     View* child = host->child_at(i);
  62     if (!child->visible())
  63       continue;
  64     total_main_axis_size +=
  65         MainAxisSizeForView(child, child_area.width()) + between_child_spacing_;
  66     ++num_visible;
  67     flex_sum += GetFlexForView(child);
  68   }
  69
  70   if (!num_visible)
  71     return;
  72
  73   total_main_axis_size -= between_child_spacing_;
  74   // Free space can be negative indicating that the views want to overflow.
  75   int main_free_space = MainAxisSize(child_area) - total_main_axis_size;
  76   {
  77     int position = MainAxisPosition(child_area);
  78     int size = MainAxisSize(child_area);
  79     if (!flex_sum) {
  80       switch (main_axis_alignment_) {
  81         case MAIN_AXIS_ALIGNMENT_START:
  82           break;
  83         case MAIN_AXIS_ALIGNMENT_CENTER:
  84           position += main_free_space / 2;
  85           size = total_main_axis_size;
  86           break;
  87         case MAIN_AXIS_ALIGNMENT_END:
  88           position += main_free_space;
  89           size = total_main_axis_size;
  90           break;
  91         default:
  92           NOTREACHED();
  93           break;
  94       }
  95     }
  96     gfx::Rect new_child_area(child_area);
  97     SetMainAxisPosition(position, &new_child_area);
  98     SetMainAxisSize(size, &new_child_area);
  99     child_area.Intersect(new_child_area);
 100   }
 101
 102   int main_position = MainAxisPosition(child_area);
 103   int total_padding = 0;
 104   int current_flex = 0;
 105   for (int i = 0; i < host->child_count(); ++i) {
 106     View* child = host->child_at(i);
 107     if (!child->visible())
 108       continue;
 109
 110     // Calculate cross axis size.
 111     gfx::Rect bounds(child_area);
 112     SetMainAxisPosition(main_position, &bounds);
 113     if (cross_axis_alignment_ != CROSS_AXIS_ALIGNMENT_STRETCH) {
 114       int free_space = CrossAxisSize(bounds) - CrossAxisSizeForView(child);
 115       int position = CrossAxisPosition(bounds);
 116       if (cross_axis_alignment_ == CROSS_AXIS_ALIGNMENT_CENTER) {
 117         position += free_space / 2;
 118       } else if (cross_axis_alignment_ == CROSS_AXIS_ALIGNMENT_END) {
 119         position += free_space;
 120       }
 121       SetCrossAxisPosition(position, &bounds);
 122       SetCrossAxisSize(CrossAxisSizeForView(child), &bounds);
 123     }
 124
 125     // Calculate flex padding.
 126     int current_padding = 0;
 127     if (GetFlexForView(child) > 0) {
 128       current_flex += GetFlexForView(child);
 129       int quot = (main_free_space * current_flex) / flex_sum;
 130       int rem = (main_free_space * current_flex) % flex_sum;
 131       current_padding = quot - total_padding;
 132       // Use the current remainder to round to the nearest pixel.
 133       if (std::abs(rem) * 2 >= flex_sum)
 134         current_padding += main_free_space > 0 ? 1 : -1;
 135       total_padding += current_padding;
 136     }
 137
 138     // Set main axis size.
 139     int child_main_axis_size = MainAxisSizeForView(child, child_area.width());
 140     SetMainAxisSize(child_main_axis_size + current_padding, &bounds);
 141     if (MainAxisSize(bounds) > 0 || GetFlexForView(child) > 0)
 142       main_position += MainAxisSize(bounds) + between_child_spacing_;
 143
 144     // Clamp child view bounds to |child_area|.
 145     bounds.Intersect(child_area);
 146     child->SetBoundsRect(bounds);
 147   }
 148
 149   // Flex views should have grown/shrunk to consume all free space.
 150   if (flex_sum)
 151     DCHECK_EQ(total_padding, main_free_space);
 152 }
 153
 154 gfx::Size BoxLayout::GetPreferredSize(const View* host) const {
 155   DCHECK_EQ(host_, host);
 156   // Calculate the child views' preferred width.
 157   int width = 0;
 158   if (orientation_ == kVertical) {
 159     for (int i = 0; i < host->child_count(); ++i) {
 160       const View* child = host->child_at(i);
 161       if (!child->visible())
 162         continue;
 163
 164       width = std::max(width, child->GetPreferredSize().width());
 165     }
 166     width = std::max(width, minimum_cross_axis_size_);
 167   }
 168
 169   return GetPreferredSizeForChildWidth(host, width);
 170 }
 171
 172 int BoxLayout::GetPreferredHeightForWidth(const View* host, int width) const {
 173   DCHECK_EQ(host_, host);
 174   int child_width = width - NonChildSize(host).width();
 175   return GetPreferredSizeForChildWidth(host, child_width).height();
 176 }
 177
 178 void BoxLayout::Installed(View* host) {
 179   DCHECK(!host_);
 180   host_ = host;
 181 }
 182
 183 void BoxLayout::Uninstalled(View* host) {
 184   DCHECK_EQ(host_, host);
 185   host_ = NULL;
 186   flex_map_.clear();
 187 }
 188
 189 void BoxLayout::ViewRemoved(View* host, View* view) {
 190   ClearFlexForView(view);
 191 }
 192
 193 int BoxLayout::GetFlexForView(const View* view) const {
 194   std::map<const View*, int>::const_iterator it = flex_map_.find(view);
 195   if (it == flex_map_.end())
 196     return default_flex_;
 197
 198   return it->second;
 199 }
 200
 201 int BoxLayout::MainAxisSize(const gfx::Rect& rect) const {
 202   return orientation_ == kHorizontal ? rect.width() : rect.height();
 203 }
 204
 205 int BoxLayout::MainAxisPosition(const gfx::Rect& rect) const {
 206   return orientation_ == kHorizontal ? rect.x() : rect.y();
 207 }
 208
 209 void BoxLayout::SetMainAxisSize(int size, gfx::Rect* rect) const {
 210   if (orientation_ == kHorizontal)
 211     rect->set_width(size);
 212   else
 213     rect->set_height(size);
 214 }
 215
 216 void BoxLayout::SetMainAxisPosition(int position, gfx::Rect* rect) const {
 217   if (orientation_ == kHorizontal)
 218     rect->set_x(position);
 219   else
 220     rect->set_y(position);
 221 }
 222
 223 int BoxLayout::CrossAxisSize(const gfx::Rect& rect) const {
 224   return orientation_ == kVertical ? rect.width() : rect.height();
 225 }
 226
 227 int BoxLayout::CrossAxisPosition(const gfx::Rect& rect) const {
 228   return orientation_ == kVertical ? rect.x() : rect.y();
 229 }
 230
 231 void BoxLayout::SetCrossAxisSize(int size, gfx::Rect* rect) const {
 232   if (orientation_ == kVertical)
 233     rect->set_width(size);
 234   else
 235     rect->set_height(size);
 236 }
 237
 238 void BoxLayout::SetCrossAxisPosition(int position, gfx::Rect* rect) const {
 239   if (orientation_ == kVertical)
 240     rect->set_x(position);
 241   else
 242     rect->set_y(position);
 243 }
 244
 245 int BoxLayout::MainAxisSizeForView(const View* view,
 246                                    int child_area_width) const {
 247   return orientation_ == kHorizontal
 248              ? view->GetPreferredSize().width()
 249              : view->GetHeightForWidth(cross_axis_alignment_ ==
 250                                                CROSS_AXIS_ALIGNMENT_STRETCH
 251                                            ? child_area_width
 252                                            : view->GetPreferredSize().width());
 253 }
 254
 255 int BoxLayout::CrossAxisSizeForView(const View* view) const {
 256   return orientation_ == kVertical
 257              ? view->GetPreferredSize().width()
 258              : view->GetHeightForWidth(view->GetPreferredSize().width());
 259 }
 260
 261 gfx::Size BoxLayout::GetPreferredSizeForChildWidth(const View* host,
 262                                                    int child_area_width) const {
 263   gfx::Rect child_area_bounds;
 264
 265   if (orientation_ == kHorizontal) {
 266     // Horizontal layouts ignore |child_area_width|, meaning they mimic the
 267     // default behavior of GridLayout::GetPreferredHeightForWidth().
 268     // TODO(estade): fix this if it ever becomes a problem.
 269     int position = 0;
 270     for (int i = 0; i < host->child_count(); ++i) {
 271       const View* child = host->child_at(i);
 272       if (!child->visible())
 273         continue;
 274
 275       gfx::Size size(child->GetPreferredSize());
 276       if (size.IsEmpty())
 277         continue;
 278
 279       gfx::Rect child_bounds(position, 0, size.width(), size.height());
 280       child_area_bounds.Union(child_bounds);
 281       position += size.width() + between_child_spacing_;
 282     }
 283     child_area_bounds.set_height(
 284         std::max(child_area_bounds.height(), minimum_cross_axis_size_));
 285   } else {
 286     int height = 0;
 287     for (int i = 0; i < host->child_count(); ++i) {
 288       const View* child = host->child_at(i);
 289       if (!child->visible())
 290         continue;
 291
 292       // Use the child area width for getting the height if the child is
 293       // supposed to stretch. Use its preferred size otherwise.
 294       int extra_height = MainAxisSizeForView(child, child_area_width);
 295       // Only add |between_child_spacing_| if this is not the only child.
 296       if (height != 0 && extra_height > 0)
 297         height += between_child_spacing_;
 298       height += extra_height;
 299     }
 300
 301     child_area_bounds.set_width(child_area_width);
 302     child_area_bounds.set_height(height);
 303   }
 304
 305   gfx::Size non_child_size = NonChildSize(host);
 306   return gfx::Size(child_area_bounds.width() + non_child_size.width(),
 307                    child_area_bounds.height() + non_child_size.height());
 308 }
 309
 310 gfx::Size BoxLayout::NonChildSize(const View* host) const {
 311   gfx::Insets insets(host->GetInsets());
 312   return gfx::Size(insets.width() + inside_border_insets_.width(),
 313                    insets.height() + inside_border_insets_.height());
 314 }
 315
 316 } // namespace views